The invention concerns a device for timbering or lining deep trenches, holes, tunnels or other excavations.
Lining devices are described in DE 4,230,860 and DE 4,404,812. In these devices, supports and support flanges are comprised of sheet steel. The lining plates are supported on the support flanges on one side, and on the other side by bracing frames standing crosswise in the trench. The bracing frames have upper and lower pairs of rollers which roll on roller tracks located on the supports so that the bracing frame and/or the supports can be moved relative to one another for raising or lowering the device into the trench. The bracing frames engage the supports via a guide channel arranged in the center of the inside (trench-facing side) of the supports. The roller tracks are formed by the outsides of the support flanges and extend on both sides of this guide channel.
When the device is in place in the trench, tensile forces may be exerted on the bracing frame by the supports, thus, the guide channel is partially enclosed by flanges on the inside of the support. The flanges define a gap between them through which parts of the bracing frame can fit thereby engaging the flange from behind, so that a form-fitting guide is achieved. In devices of this type, the parts engaging in a form-fitting manner in the guide channel are T-shaped rails, whose flanges slide on the inside of the flanges of the guide channel.
It has been shown that in devices for lining deep trenches, not only very high compressive forces are exercised on the bracing frame, but also very high tensile forces, which must be taken up by parts of the bracing frame that engage the flanges of the guide channel from behind. These forces are particularly great in the upper region of the bracing frame, if, when the pair of supports is driven into the earth, these parts do not stand precisely parallel to one another, but rather their lower ends stand at a shorter distance from one another than their upper ends. These tensile forces induce such large friction forces, that a shifting of the bracing frame relative to the supports is difficult.